Add flag to restart place-and-route on failed target frequency #1373
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* Add --restart-on-failed-target-frequency flag and logic to restart the place-and-route process if the target frequency is not achieved. * This flag is intended to be used with the --randomize-seed option to generate a new random seed for every run. This can significantly improve the chances of achieving a higher clock frequency compared to using the default seed. * Move print_net_source out of log_crit_paths() to remove the 'static' keyword, which could otherwise cause a segmentation fault if the context is changed.
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Personally I think this should be out of scope for nextpnr. And instead should be handled with an external script. One reason is that in most cases nextpnr is single threaded, the only parallelism by default is the analytical placer and only if you build with openmp support. So if you are on the edge of pass fail you will want to run nextpnr n times in parallel since it will be much faster to find a matching seed. If you want I can send such a python script, but it was for fixed domain names. It shouldn't be to hard to adjust for arbitrary domains. |
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Yeah, I'm in agreement with @rowanG077 Anything in nextpnr itself should be finer-grained, like improving the ripup-and-reroute support in the router to locally improve the critical path. |
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Add --restart-on-failed-target-frequency flag and logic to restart the place-and-route process if the target frequency is not achieved.
This flag is intended to be used with the --randomize-seed option to generate a new random seed for every run. This can significantly improve the chances of achieving a higher clock frequency compared to using the default seed.
Move print_net_source out of log_crit_paths() to remove the 'static' keyword, which could otherwise cause a segmentation fault if the context is changed.